Scanning Photocurrent and Photoluminescence Imaging of Frozen Polymer Light Emitting Electrochemical Cells
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Authors
Inayeh, Alex
Date
2013-05-29
Type
thesis
Language
eng
Keyword
OBIC , polymer , optical scan , LEC , optical beam induced current , light emitting electrochemical cells , photocurrent
Alternative Title
Abstract
A polymer light-emitting electrochemical cell (LEC) is a solid-state polymer device operating according to in situ electrochemical doping and the formation of a light-emitting polymer p-n junction. This operating mechanism, however, has been the subject of much debate. Planar LECs with millimeter scale interelectrode spacings offer great advantages for directly observing the electrochemical doping process. Photoluminescence quenching and the formation of a light-emitting junction have been observed in planar polymer LECs, demonstrating the existence of electrochemical doping. The chemical potential difference between the p- and n-doped regions creates a built-in potential/electric field in the junction region, which can be probed by measuring the optical beam induced current (OBIC).
This study utilizes a versatile and easy-to-use method of performing OBIC analysis. The OBIC and photoluminescence profiles of LECs have been simultaneously measured by scanning a focused light beam across large planar LECs that have been turned on and cooled to freeze the doping profile. The photoluminescence intensity undergoes a sharp transition between the p- and n-doped regions. The OBIC photocurrent is only observed in the transition region that is narrower than the width of the excitation beam, which is about 35 μm. The results depict a static planar polymer p-n junction with a built-in electric field pointing from n to p. The electrode interfaces do not produce a measurable photocurrent indicating ohmic contact.
Description
Thesis (Master, Physics, Engineering Physics and Astronomy) -- Queen's University, 2013-05-28 12:52:14.171
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This publication is made available by the authority of the copyright owner solely for the purpose of private study and research and may not be copied or reproduced except as permitted by the copyright laws without written authority from the copyright owner.